Gwen Stafani Galvin Rossdale, Jennifer Meyer, Sara Gilbert, Jessica Alba, Cash Warren, Ellen Pompeo

Gwen Stafani Galvin Rossdale, Jennifer Meyer, Sara Gilbert, Jessica Alba, Cash Warren, Ellen Pompeo

Happy Birthday, Harlow!

Nicole Richie and Joel Madden's baby girl turns three on January 11th and the b-day girl already had a celebrity-studded party on Saturday to celebrate the big day. Guests included her bro Sparrow (pictured above with mom Nic), Kourtney Kardashian and baby Mason, Gwen Stefani and Gavin Rossdale with their two boys and Jessica Alba and Cash with baby Honor... to name a few!

The super-cute shindig happened at the Tree House Social Club in Beverly Hills yesterday afternoon - take a look inside our MONSTER gallery below to see all the pics of these Hollywood stars and their tots!